The present invention relates to a guide vane assembly for a turbomachine, a turbomachine, and a method for installing a guide vane assembly.
Turbomachines such as aircraft engines and stationary gas turbines often have at least one guide vane assembly for the adjustment of optimal operating conditions. This ring comprises an inner ring and a plurality of guide vanes, one end of which is arranged on the inner ring, and these guide vanes extend radially outward, starting from this point; the terms “radial”, “axial” and “in the peripheral direction” in this document always pertain—unless otherwise indicated—to a central geometrical axis of the guide vane assembly or the inner ring, which is not always additionally stipulated for better readability. Insofar as the respective indications pertain to individual parts of the guide vane assembly, they are to be understood in relation to the designated orientation of the respective individual part in the guide vane assembly.
A guide vane assembly may have an adjustable design, in particular; in this case, the guide vanes are able to swivel about a designated swivel axis, which generally corresponds to a lengthwise axis of the guide vanes and runs substantially radially. The swiveling may occur by way of external adjustment components on the guide vanes, especially by means of adjusting pins, which are inserted or can be inserted into corresponding uptakes of the casing and which then can interact with a corresponding adjustment device on the external casing.
An internal stabilization of the guide vanes in known guide vane assemblies is often carried out by way of bearing pins, which extend radially inward from a respective guide vane plate and which may be introduced into bearing bushes of the inner ring.
In EP 2 696 041 A1, an adjustable guide vane assembly is proposed, in which the guide vanes are mounted each time in bearing members having a block-like basic shape and a bearing bore. In this case, the inner ring is composed of two half-rings, which are shoved onto the bearing member in the peripheral direction. Such a guide vane assembly affords the advantages of an easy assembly, in particular.
However, due to manufacturing tolerances or vibrations, recirculation of air may occur through gaps at the edge surfaces of the bearing members. This reduces the efficiency of the turbomachine.